More than 1,000 flights were cancelled across the US on Friday as an emergency order from the Federal Aviation Administration (FAA) took effect, forcing airlines to cut services at 40 of the country's busiest airports. FlightAware also counted more than 4,300 delays on the first day.

The order, announced on Wednesday by Transportation Secretary Sean Duffy and FAA Administrator Bryan Bedford, requires airlines to cut 4 percent of domestic flights at the affected airports between 6am and 10pm. International flights are exempt. The reductions deepen in stages if the funding standoff continues: 6 percent by 11 November, 8 percent by 13 November and 10 percent by 14 November.

Atlanta's Hartsfield-Jackson, the world's busiest airport, is among the 40, along with Dallas-Fort Worth, Denver, Los Angeles and Charlotte, and the airports serving New York, Chicago, Washington, Houston, Miami, San Francisco and Orlando. Airlines choose which flights to cancel, and face a fine of $75,000 for each flight operated above their limit.

The FAA says the cuts are a safety measure. About 13,000 air traffic controllers and 50,000 airport screeners have worked without pay since the federal government shutdown began on 1 October, and the agency was already about 3,500 controllers short of its target before the shutdown. Absenteeism has risen above 30 percent at some airports.

The shutdown reached its 38th day on Friday, making it the longest in American history, passing the 35-day record set in 2018 and 2019. Aviation analytics firm Cirium estimates that at the full 10 percent cut, about 1,800 flights and 268,000 seats a day would be affected. Mr Duffy has warned of "mass chaos", including delays, cancellations and possible airspace closures, if the shutdown drags on towards Thanksgiving on 26 November. Read the full report on US News Pulse.